<!--IPTC: A worker cleans and lubricates the head of the machine, after the stimulation hydraulic fracturing of one segment of the well is finished, at Southwestern Energy Co.'s natural gas production site at the Marcellus Shale formation in Camptown, Pennsylvania, U.S., on Wednesday, Oct. 19, 2011. The Marcellus Shale, located in the U.S. Northeast, contains natural gas, which is obtained through hydraulic fracturing, a technique in which millions of gallons of water, sand and chemicals are pumped underground to break apart the rock. Photographer: Julia Schmalz/Bloomberg-->

An independent audit of Colorado’s oil and gas regulations on hydro-fracturing — a technique used in drilling almost all wells in the state — identified four areas where the rules should be tightened.

The audit by State Review of Oil and Natural Gas Environmental Regulations Inc., which is composed of environmental groups and state oil and gas regulators, found the Colorado programs “well-managed and professional” and meeting the group’s hydrofracturing guidelines.

The audit, requested by the Colorado Oil and Gas Conservation Commission, identified areas in which the state could improve its oversight:

• Set a minimum amount of surface casing for a well to protect groundwater. Colorado does not have a requirement.

• Include details of fracking fluids as part of the well-completion form a driller files with the state.

• Evaluate available sources of water for use in hydraulic fracturing. “Given the significant water-supply issues in this arid region, this project should also include an evaluation of whether or not availability of water for hydraulic fracturing is an issue,” the audit said.

The owners of Boulder’s Sterling University Peaks apartments, who this summer were cited for illegally subdividing 92 bedrooms in the complex, have reached an agreement to settle the case for $410,000, the city announced Thursday.